The present invention relates generally to locking devices for selectively securing inner and outer telescoping cylindrical tubes in the desired relationship. Particularly, the invention relates to a locking collar for adjusting the height of portable hospital equipment such as stands for IV bottles and the like.
Although the present invention is suited for many other uses, it was developed specifically for use with adjustable IV bottle stands which are characterized by an outer cylindrical tube supported on a roller base, and an inner cylindrical tube having bottle supporting hooks at its upper end which is disposed in telescoping relation within the outer tube. The inner tube is moved to a lower loading position to attach the IV bottles to the bottle hooks, and is then raised to its normal operating height to provide the proper gravity feed to a patient. The present invention comprises a novel locking collar located at the upper end of the outer tube which permits a selective locking of the inner tube in any desired position.
Height-adjustable stands employing telescoping cylindrical tubes have been used for a variety of purposes. Some familiar uses include music stands, camera tripods and light stands. A typical arrangement for adjusting the height of the tubes is a lock screw passing through the outer tube and bearing against the inner tube. Although effective to a degree, such arrangements provide a limited clamping force, often resulting in the slippage of the tubes and sometimes a complete collapse of the mechanism. Furthermore, the screw bearing against the surface of the inner tube will in time have a destructive effect on the tube surface giving an unsightly appearance to the device and eventually interfering with the proper sliding and locking movement of the tubes.
Slippage of the tubes is in most such devices merely an annoyance but in hospital equipment and particularly patient care equipment such as IV stands, the slippage could have serious consequences since the loss of heigh of the supported bottles would diminish the pressure head of the fluid and interfere with its proper delivery to the patient. Accordingly, for hospital use a locking collar is required which provides a non-slip grip of the stand members but which can be readily unlocked and relocked without unreasonable effort.